Abstract : Red blood cell storage can result in depression of erythrocyte 2,3,-diphosphoglycerate (DPG) levels, thereby increase oxy-hemoglobin affinity and potentially decrease capillary-to-tissue oxygen transport. We assessed the metabolic and functional effects which resulted from red blood cell storage by using an isolated rabbit heart preparation with an isovolumic left ventricular balloon. Coronary flow was held constant to simulate the physiology of coronary atherosclerosis and other conditions of limited coronary vasodilator reserve where coronary flow cannot increase in response to an increase in myocardial oxygen demand. Myocardial function and metabolism were measured under basal conditions and during isoproterenol stress at 37 and 30 C. The coronary arterial perfusate was alternated between red blood cell suspensions composed of either high or low oxy-hemoglobin affinity red blood cells.